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In this paper, we consider Mobile WiMAX and LTE as the future technologies for primary OFDMA systems and study dynamic spectrum access (DSA) for unlicensed systems coexisting with primary OFDMA systems. We propose an effective DSA scheme that allows an unlicensed system to statistically and opportunistically access the whole spectrum bandwidth during the last consecutive symbols of each primary OFDMA...
The large amount of peer-to-peer (P2P) traffic in today's Internet represents a great challenge for most Internet Service providers (ISPs). P2P traffic does not conform to traditional ISP traffic policies, and it makes it harder to perform traffic engineering in the network. It is especially the peer-selection mechanism of the P2P application that influences the traffic patterns and creates an imbalance...
Dealing with link breaks in MANETs is a challenge for the routing protocol. This paper proposes a mechanism to reduce the negative impact of link breaks on the routing. The transmission area of a node is divided into a safe zone close to the node and an unsafe zone (i.e. buffer zone) near the end of the transmission range. The probability is high that link breaks occur with neighboring nodes located...
An increasing number of research efforts on wireless sensor networks (WSNs) are now considering dynamic environments with heterogeneous sensor devices. Most of this research considers data, control, and management issues separately and not clearly within a common architecture. This paper presents our development of an architecture, namely DCM-Arch, to address these issues together. The architectureconsists...
Due to frequent link failures in multi-hop wireless networks, redundancy can be an important feature. For example, when planning the structure of a backhaul mesh network for public access, it is common to introduce redundant nodes in the mesh network. These are called redundant, because they do not increase the network capacity under normal operation, due to the shortest-path metric of the routing...
There is a large body of work addressing information storage, reduction, and dissemination in Wireless Sensor Networks (WSNs), but there seems to be no contribution giving a survey of this literature. In this paper we take on such a challenge and review previous WSN research and further presents a framework that we use for classifying the different proposed approaches and techniques. The framework...
When planning the structure of a backhaul mesh network for public access, it is common to introduce redundant nodes in the mesh network. These are called redundant, because they do not increase the network capacity under normal operation, due to the shortest-path metric of the routing protocol. Instead, their sole purpose is to increase the network reliability by providing failover links when a link...
This paper presents a unique approach for a model-based admission control algorithm for the IEEE 802.11e enhanced distributed channel access (EDCA) standard. The analytical model used as the foundation for the algorithm covers both nonsaturation and saturation conditions. This allows us to keep the system out of saturation by monitoring several variables. Since the medium access delay represents the...
A number of works have focused on the mean delay performance of IEEE 802.11. The main contribution of this paper is that it provides a method to obtain the full distribution of the delay, and not only mean values or higher order moments. Hence, any desirable delay percentiles can be found. The distribution is found by inverting the z-transform of the delay numerically. The trapezoidal rule is used...
A number of analytical models have been proposed to describe the priority schemes of the enhanced distributed channel access (EDCA) mechanism of the IEEE 802.11e standard. EDCA provides a class-based differentiated quality of service (QoS) to IEEE 802.11 WLANs. Many have used a multiple number of nodes to study the differentiation behaviour of the model. However, in many real-life usage scenarios...
An analytical model is proposed to describe the priority schemes of the enhanced distributed channel access (EDCA) mechanism of the IEEE 802.11e standard. EDCA provides class-based differentiated quality of service (QoS) to IEEE 802.11 WLANs. The main contribution of this paper opposed to other works is that the model predicts the full delay distribution through its z-transform. Furthermore, the mean...
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